MODIFIED FOURIER-TRANSFORM LIGHTNING SURGE ANALYSIS OF AN OVERHEAD LINE-UNDERGROUND COAXIAL (CV) CABLE SYSTEM .2. SYSTEM LIGHTNING SURGE RESPONSE

The lightning surge analysis of an overhead line-underground CV cable transmission system has been carried out using the modified Fourier tr ansform with a multiconductor representation. The frequency dependence of the transmission system components such as the overhead transmissi on line, underground cable and towers has been analyzed. A digital sim ulation based on this analysis has been developed and applied to a 77 kV three-phase single-circuit system. The results for a direct hit by a lightning stroke at the riser pole tower top show that the overvolta ges at the riser pole increase with increase in the tower footing resi stance and that the phase conductor overvoltages are greatly affected by the CV cable. The cable open-tie overvoltages decrease with increas e in the cable length.